Base layers & thermals
The foundation in your layering system. Choose a warmth level and think about your activity output to get started.
Base layers
Solid base layers are the foundation of any outdoor activity. Whether you’re tackling local trails, bagging bucket-list summits or hitting the slopes, base layers like thermal leggings, tops and thermal socks are an essential part of staying warm and comfortable all day.
Merino wool base layers vs. synthetic base layers
Merino wool base layers are soft, breathable and naturally antimicrobial. They’re ideal for activities where you don’t work up too much of a sweat, like camping trips, leisurely hikes and downhill skiing.
Synthetic base layers are made from high-performance polyester or polypropylene. Lightweight and quick-drying, they’re also usually more durable and budget-friendly than merino wool. Synthetic base layers shine during high-output activities like trail running, cross-country skiing and mountain biking.
Merino-synthetic base layers offer the best of both worlds, with the durability of synthetic fabrics and the temperature-regulating qualities of wool.
For more information on how to choose the right base layers, read our how to choose the right base layers guide.
How to use your base layers
Once you’ve picked your base layers, add a mid-layer and outer layer based on your activity and the weather.
Mid-layers use fleece and insulation to trap body heat and move moisture outward. An outer layer is your shell against rain, snow and whatever else nature throws your way.
Learn how to create a layering system to handle the elements all year long.